Chapter 5

Question 1

importance of play

Answer 1

• play is one of the defining behaviors of mammals
• mammals have instinctive tendencies to engage in this complex behavior
• is categorized in the more specific discipline of neuroethology (the study of the neural basis of animals’ natural behaviors
• helps animals learn about their physical and social environments

Question 2

What three behaviors are assessed when researchers observe play?

Answer 2

• chasing
• dorsal contacts (in which one animal climbs on another’s back
• pins (in which one animal flips another onto its back and pounces on top of its belly

Question 3

Subcortical areas of the brain

Answer 3

mesolimbic dopamine system is important for reward aspects of play

Thalamus

• parafascicular area
• ->Regulate somatosensory input necessary for choreographing specific play responses along with the striatum influence on intentional movement patterns
• Periaqueductal gray area
• ->Regulate play response

Question 4

what reduces play duration?

Answer 4

amphetamine and methylphenidate significantly reduce play duration, perhaps b/c of an increase in norepinephrine

Question 5

DNA methylation

Answer 5

a mechanism in which genes can be modified by the addition of a methyl chemical compound to the cytosine nucleotide base in DNA, usually preventing expression of the gene

Question 6

Pluripotent

Answer 6

new cells during the earliest stages of development are able to become many different types of cells

Question 7

Stem cells

Answer 7

the category of cells that are able to become many different types of cells

Question 8

progenitor cells

Answer 8

another category of rapidly dividing cells

• Although they retain their ability to eventually produce a specific type of cell, they do not have the ability of stem cells to produce pluripotent (unspecialized) cells
• More specialized than stem cells

Question 9

radical cells

Answer 9

• a type of glial cell that play an extremely important role in the developing cortex by providing a pathway for developing neurons to follow to their destinations
• serve as guidance paths for immature neurons, marking the way to their final destination
• may turn into astrocytes or just continue to exist

Question 10

Nerve growth factor (NGF)

Answer 10

facilitates the growth of axons and dendrites and enhances the probability of neuronal survival

Question 11

discovery of NGF marked the beginning of the identification of what additional neurochemicals

Answer 11

Brain-derived neurotrophic factor (BDNF)

Cell-adhesion molecules (CAMs)

Question 12

3 layers of developing embryo

Answer 12

• A zygote is a fertilized egg.
• A human embryo will develop three cell layers:
  1. Ectoderm
  2. Mesoderm
  3. Endoderm
• Ectoderm, the outer layer, becomes the nervous system.
• -> The neural groove forms between ridges of the ectoderm.

Question 13

Merzenich finger study

Answer 13

In as key study Merzenich and his colleagues amputated the third finger on an adult owl monkey’s hand and waited up to 8 months to see whether the monkey’s brain had reorganized itself to accommodate the loss of the finger

Just two months after losing a digit, the owl monkey cortical area representing each digit reorganizing to compensate for the lost incoming sensory information from ht lost digit maximizing responsiveness of the remaining digits

Question 14

alzheimer’s disease

Answer 14

Characterized by severe memory loss an eventual loss of essential function such as swallowing, increases dramatically with age

(a) Alzheimer’s disease is characterized by amyloid plaques interrupting neuronal functioning, especially in the hippocampal area.
(b) Normally, tau works to stabilize microtubules, but in Alzheimer’s disease τ destabilizes microtubules, leading to neurofibrillary tangles and diminished neuronal processing and communication
(c) Patients with Alzheimer’s also show enlarged ventricles tubules, and significant shrinkage of the cortical and hippocampal areas.

Question 15

Epigenetics

Answer 15

The environment can directly impact genetics

Key Experiment:
Offspring born to high-licking maternal rats exhibit less anxiety in the elevated plus maze compared with offspring from low-licking maternal rats

(a) Variation in the amount of maternal contact with the pups can have long-lasting neuronal and behavioral effects.
(b) One study of the influence of maternal care on the anxiety of the offspring used an elevated-plus maze. Rats that spent more time in the open arm were considered less anxious, and those that spent more time in the closed arm were considered more anxious.
(c) Rats who had been more frequently licked by their mother spent more time in the central area and open arm.

Question 16

What happens when the brain is injured?

Answer 16

• when a person suffers an automobile accident causing the brain to slam against the inside of the skill
  → damage occurs as axons twist and tear, a process known as axon shearing
  → Often leads to a subdural hematoma (a localized blood clot)

If glucose and oxygen isn’t delivered to the cell (through the process of cerebral blood flow), the cell enters a phase of ionic flux, characterized by altered concentrations of ions such as decreased levels of magnesium and potassium and increased levels of calcium
Fail to locate resources → cell will die

Question 17

Ischemia

Answer 17

disruption of blood flow

Question 18

how does the brain recover from injury

Answer 18

• Training is critical to recovery
• Constraint-induced therapy
• younger brains cope better than older brains

Question 19

constraint-induced therapy

Answer 19

• Require patients to use the affected limb(s) rather than providing a work around
• Restricts the use of the functional limb to encourage the use of the impaired limb

Question 20

chronic traumatic encephalopathy (CTE)

Answer 20

• a condition due to head injuries from boxing, originally referred to as dementia puglistica or punch-drunk syndrome, that appears to result in progressive neurological deterioration
• atrophy to several brain regions
• behavioral/personality changes
• movement difficulties

Question 21

cortical variations

Answer 21

the functional areas of the cortex change in accordance with the sensory and motor needs for the specific species’ arrival

Question 22

Brain-derived neurotrophic factor (BDNF)

Answer 22

promotes the maturation of neurons and synapse formation throughout the brain

• Implicated in complex behaviors such as learning and in disorders such as depression
• Absence of forebrain BDNF early in development is associated with disruption of learning processes

Question 23

Cell-adhesion molecules (CAMs)

Answer 23

• membrane proteins located on the cell’s surface that react differently to other cell surfaces and, by being attracted to certain proteins located on specific types of cells, provide one manner of neuron migration

Question 24

key stages in the process of transitioning a burgeoning undifferentiated cell into a specific type of neuron that will eventually be incorporated into neural network

Answer 24

a) following neurogenesis, the cells must migrate to a specific geographical area of the developing brain where similar types of neurons will aggregate
b) Following this aggregation phase of development, the cells continue to differentiate, forming neural communities consisting of similar types of neurons
c) Functional circuits are formed as synaptogenesis (the formation of new synapses among neurons) occurs
d) Some neurons will be deemed unnecessary during circuit formation and will defnerate via a form of programmed cell death known as apoptosis

e) Often synapse rearrangement will take place as neurons are pruned throughout the brain
- Pruning process removes unnecessary cells so that neuronal processes once attached to now-degenerated cells must find new cells with which to form synapses

Question 25

brain development

Answer 25

the development of the human brain occurs at a rapid pace. early in the process, the overall brain structure is similar to that of other mammals, with the more specific differentiation characteristic of the human brain occurring toward the end of gestational development

Question 26

proliferative

Answer 26

cell producing